In the prior art, epoxy resins are commonly used as optical materials for use in optical devices and optical parts, typically encapsulating materials in light-emitting diode (LED) devices. Also, attempts are made to use silicone resins as molding material for LED devices (JP-A H10-228249 and JP-A H10-242513) and as color filter material (JP-A 2000-123981). In practice, few silicone resins are used.
Although the epoxy resins have several problems as encapsulant such as yellowing by UV or radiation, and cracking by an increased heat release associated with size reduction, these problems have not been considered serious. As white LEDs are recently of greater interest, it is urgently required to address the problems of epoxy resins. One approach is to use a silicone resin having a multiplicity of phenyl groups in the molecule as encapsulant (JP-A 2010-180323).